Thursday, July 09, 2009

A brief history of man

The narrative of human evolution, in spite of Darwin and his Origin of Species, is a discontinuous mishmash that gives us only a broad outline of who we are and where we come from. The evidence for the study of human evolution is derived primarily from fossils, which can give insights into the existence of in-between species — the ones that provide the missing links in the evolution of man.

Hamburg in Germany is the site of an annual fossil fair where scientists, private collectors, dealers and locals converge in December every year to peddle their pre-historic wares. Jorn Hurum, associate professor of paleontology at the Natural History Museum at the University of Oslo, is a regular at the fair, visiting every year in the hope of adding to the museum’s substantial collection.

In 2006, Hurum and a museum colleague were milling around the table of Thomas Perner, a prominent dealer. Hurum had had a long association with Perner, and so, when the latter asked him to meet up for a drink later that day, with a mischievous twinkle in his eye, Hurum acceded readily.

Over drinks, Perner explained to Hurum that a private collector seeking anonymity had given him six months to sell a rare find. Perner opened an envelope and showed Hurum a high-resolution colour photograph of a complete fossil skeleton. The photograph was of Ida (so named by Hurum later), fossilised after her death.

Ida is the world-renowned 47-million-year-old primate ancestor whose perfectly fossilised remains were shown to Hurum on that fateful December day. Her discovery is massively important to science because she could provide the crucial missing link in the evolution of primates. It was during the Eocene (56 million years to 34 million years ago) that a spilt in two distinct primate groups had occurred, leading to the existence of humankind.

Because of gaps in fossil records, paleontologists have had to hypothesise about what happened after the primitive primate. Their best guess so far had been that by 40 million years ago there were two distinct primate groups: those with wet noses—lemurs and lorises; and those with dry noses—tarsiers, apes, monkeys and humans. It was Ida that could explain the split in primate evolution.

Barely a year old at the time of her death, Ida died while drinking from a lake in what was then a tropical rain forest. A volcanic eruption engulfed the area surrounding the lake and the dense gas it released rendered Ida unconscious. Her limp body fell into the lake, settling in the sediment at the bottom, which over time, congealed into oily shale. A perfect accident had created the conditions for long-term preservation.

The site where this occurred is located near the village of Messel in Germany. Called the Messel Pit, it is a rich source of fossils from the Middle Eocene period. Up until the beginning of the twentieth century, the Messel Pit was chiefly a quarry, mined by coal prospectors looking to convert the shale into raw petroleum.

However, beginning 1966, formal excavations were undertaken by paleontologists and archaeologists in the Messel Pit. “Fossils of horses, fish, bats and crocodiles perfectly frozen in time were unearthed and preserved. In many cases, complete skeletons were preserved, along with bacterial imprints of hair, feathers, scales and even internal organs,” writes Tudge.

By 1971, mining had ceased in the area and it became open hunting ground for scientists and private collectors alike. Sometime in 1982, a private collector from Frankfurt, while splitting the layers of shale, “stumbled on a fossil of what looked like an exotic monkey crushed to the thickness of a silver dollar.” He took it home and preserved it, away from the eyes of science and the public, until twenty-five years later, when advancing age made him approach Perner.

The Link is the gripping account of how Hurum set about meeting the $1 million price tag on Ida—seeking the assistance of the Oslo museum whose director remarked, “We’re not a museum known around the world like the Louvre, but this could be our Mona Lisa”; authenticating the fossil by means of X-rays and CT scans; and clearing legal hurdles to enable the specimen to leave Germany.

Fans of Bill Bryson and Stephen Jay Gould may find the book lacking in flamboyance, but Tudge’s subject matter makes up for any deficit in flair. There are brilliant illustrations in the book, including three-dimensional images of Ida’s skeleton and close shots of her last meal. Tudge builds on the massiveness of the findings to argue about the need for humans to preserve the environment—there is an amusing, yet gravid, comparison of time lines to drive home the magnitude of destruction that human beings have wreaked in their rather minuscule time on earth.

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